Road safety evaluation through automatic extraction of road horizontal alignments from Mobile LiDAR System and inductive reasoning based on a decision tree

13 p.Safe roads are a necessity for any society because of the high social costs of traffic accidents. This challenge is addressed by a novel methodology that allows us to evaluate road safety from Mobile LiDAR System data, taking advantage of the road alignment due to its influence on the accident rate. Automation is obtained through an inductive reasoning process based on a decision tree that provides a potential risk assessment. To achieve this, a 3D point cloud is classified by an iterative and incremental algorithm based on a 2.5D and 3D Delaunay triangulation, which apply different algorithms sequentially. Next, an automatic extraction process of road horizontal alignment parameters is developed to obtain geometric consistency indexes, based on a joint triple stability criterion. Likewise, this work aims to provide a powerful and effective preventive and/or predictive tool for road safety inspections. The proposed methodology was implemented on three stretches of Spanish roads, each with different traffic conditions that represent the most common road types. The developed methodology was successfully validated through as-built road projects, which were considered as “ground truth.”S

On the use of airborne laser scanning data to verify and enrich road network features

High-resolution digital terrain models (DTM) provide accurate descriptions of our surrounding with respect to its 2.5D shape. Besides that existing cartographic databases provide detailed 2D representations of topographic objects. Integrated products, which combine both planimetric and height information are rare. This paper proposes an algorithm to elaborate the outline of a road. It is founded on a well-known line simplification algorithm. Prior information is used to guide the interpretation process. Hypothesize and test methods based on support functions are used for decision-making. Robust estimation techniques are used to derive the outline of roads. Results and a discussion, which covers qualitative aspects, are given for different types of roads. The paper ends with a conclusion and a glimpse on future work. 1

Assigning the 3rd Dimension to Roads by Use of Laser Scanning Data

Most geographic data sets available today mainly provide two-dimensional geometric information about topographic objects in different aggregation levels. Three dimensional information is distributed separately by means of digital terrain models. In contrast, many applications presume that integrated data sets are available. The extraction of man-made objects from images and laser scanner data has been in the focus of image processing research in recent years. In this paper an approach is presented to identify road objects in laser scanner data sets. The information that is of interest is the outline of the road, its height and further tributary properties like longitudinal and transversal slope, width and curvature. In order to derive the width and further properties of roads, features and attributes of 2D data sets have to be evaluated against their contribution to the integration of height information into a common data model. Planning and construction facilities make use of standardised longitudinal and cross sections. Topographic data sets only contain the middle axis of roads. In this paper the information will be detected, analysed and measured by a model based approach, investigating the neighbourhood of two dimensional road elements in terms of cross sections. After the optimal position of the section is detected, the road parameters can be refined by an estimation procedure. It is subject to further investigations where and how to introduce cross sections into a common data model with respect to handling, storage and quality aspects

RECONSTRUCTION OF ROADS FROM DENSE DIGITAL TERRAIN MODELS

High resolution digital terrain models (DTM) provide accurate descriptions of our surrounding with respect to its 2.5d shape. Besides that existing cartographic databases provide detailed 2d representations of topographic objects. Integrated products which combine both planimetric and height information are rare. Many users could benefit from integrated datasets. This integrating approach uses a segmentation algorithm that is founded on a line simplification algorithm in principle. Advance information is used to match a set of model features against a set of data features. Hypothesize and test facilities are based on support functions. Results and discussion covering qualitative aspects are given for different types of roads. The paper ends with a conclusion and a glimpse on future work

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extraction by use of airborne lase

A WEB BASED AND TIME DEPENDENT VISUALISATION OF AN EVENT CALENDAR ABSTRACT

The University of Hannover maintains a service to request an event calendar for a certain time period. This paper describes an approach to communicate such temporal information adequately and intuitively through a dynamically generated webpage including an adaptive map. The geometries requested through a Web Feature Service (WFS) are transformed into an SVG image which allows for individual visualisations of the geometries. In our case, depending on the fact if and when an event is taking place, the objects of interest are highlighted in a certain manner. The buildings with an event today are more emphasised than the buildings with an event tomorrow. In order to realise that, new ways for visualising spatial information have to be found. For example a multirepresentation database (MRDB) serves as a basis for the geospatial data. This kind of database structure allows e.g. for multiscale maps, representing the object of interest with a higher resolution than the background objects. The application serves for two main user groups: On the one hand for internet users working with a desktop PC, but on the other hand also a mobile device friendly version will be provided.